Publications

2017

This dataset combines several published datasets to create a comprehensive set of greenhouse gas emission pathways for every country and Kyoto gas covering the years 1850 to 2014 and all UNFCCC (United Nations Framework Convention on Climate Change) member states as well as most non-UNFCCC territories. The data resolves the main IPCC (Intergovernmental Panel on Climate Change) 1996 categories. For CO₂ from energy and industry time series for subsectors are available.

Benchmarks to guide countries in ratcheting-up ambition, climate finance, and support in an equitable manner are critical but not yet determined in the context of the Paris Agreement1. We identify global cost-optimal mitigation scenarios consistent with the Paris Agreement goals and allocate their emissions dynamically to countries according to five equity approaches. At the national level, China's Nationally Determined Contribution (NDC) is weaker than any of the five equity approaches, India's and the USA's NDC are aligned with two, and the EU's with three. Most developing countries’ conditional (Intended) NDCs (INDCs) are more ambitious than the average of the five equity approaches under the 2 °C goal. If the G8 and China adopt the average of the five approaches, the gap between conditional INDCs and 2 °C-consistent pathways could be closed. For an equitable, cost-optimal achievement of the 1.5 °C target, emissions in 2030 are 21% lower (relative to 2010) than for 2 °C for the G8 and China combined, and 39% lower for remaining countries. Equitably limiting warming to 1.5 °C rather than 2 °C requires that individual countries achieve mitigation milestones, such as peaking or reaching net-zero emissions, around a decade earlier.

To assess the history of greenhouse gas emissions and individual countries' contributions to emissions and climate change, detailed historical data are needed. We combine several published datasets to create a comprehensive set of emissions pathways for each country and Kyoto gas, covering the years 1850 to 2014 with yearly values, for all UNFCCC member states and most non-UNFCCC territories. The sectoral resolution is that of the main IPCC 1996 categories. Additional time series of CO2 are available for energy and industry subsectors. Country-resolved data are combined from different sources and supplemented using year-to-year growth rates from regionally resolved sources and numerical extrapolations to complete the dataset. Regional deforestation emissions are downscaled to country level using estimates of the deforested area obtained from potential vegetation and simulations of agricultural land. In this paper, we discuss the data sources and methods used and present the resulting dataset, including its limitations and uncertainties. The dataset is available from doi:10.5880/PIK.2016.003 and can be viewed on the website accompanying this paper (http://www.pik-potsdam.de/primap-live/primap-hist/)

This dataset combines several published datasets to create a comprehensive set of greenhouse gas emission pathways for every country and Kyoto gas covering the years 1850 to 2014 and all UNFCCC (United Nations Framework Convention on Climate Change) member states as well as most non-UNFCCC territories. The data resolves the main IPCC (Intergovernmental Panel on Climate Change) 1996 categories. For CO₂ from energy and industry time series for subsectors are available.

In June 2015, the G7 agreed to two global mitigation goals: ‘a decarbonization of the global economy over the course of this century’ and ‘the upper end of the latest Intergovernmental Panel on Climate Change (IPCC) recommendation of40%–70%reductions by 2050 compared to 2010’. These IPCC recommendations aim to preserve a likely (>66%) chance of limiting global warming to 2°C but are not necessarily consistent with the stronger ambition of the subsequent Paris Agreement of ‘holding the increase in the global average temperature to well below 2°C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5°C above pre-industrial levels’. The G7 did not specify global or national emissions scenarios consistent with its own agreement. Here we identify global cost-optimal emissions scenarios from Integrated Assessment Models that match the G7 agreement. These scenarios have global 2030 emissions targets of 11%–43% below 2010, global net negative CO2 emissions starting between 2056 and 2080, and some exhibit net negative greenhouse gas emissions from 2080 onwards. We allocate emissions from these global scenarios to countries according to five equity approaches representative of the five equity categories presented in the Fifth Assessment Report of theIPCC(IPCCAR5): ‘capability’, ‘equality’, ‘responsibility-capability-need’, ‘equal cumulative per capita’ and ‘staged approaches’. Our results show that G7 members’ Intended Nationally Determined Contribution (INDCs) mitigation targets are in line with a grandfathering approach but lack ambition to meet various visions of climate justice. The INDCs of China and Russia fall short of meeting the requirements of any allocation approach. Depending on how their INDCs are evaluated, the INDCs of India and Brazil can match some equity approaches evaluated in this study.

Achieving the collective goal of limiting warming to below 2 ◦ C or 1.5 ◦ C compared to pre-industrial levels requires a transition towards a fully decarbonized world. Annual greenhouse gas emissions on such a path in 2025 or 2030 can be allocated to individual countries using a variety of allocation schemes.We reanalyse the IPCC literature allocation database and provide country-level details for three approaches.At this stage, however, it seems utopian to assume that the international community will agree on a single allocation scheme. Here, we investigate an approach that involves a major-economy country taking the lead. In a bottom-up manner, other countries then determine what they consider a fair comparable target, for example, either a ‘per-capita convergence’ or ‘equal cumulative per-capita’ approach. For example, we find that a 2030 target of 67% below 1990 for the EU28, a 2025 target of 54% below 2005 for the USA or a 2030 target of 32% below 2010 for China could secure a likely chance of meeting the 2°C target in our illustrative default case. Comparing those targets to post-2020 mitigation targets reveals a large gap. No major emitter can at present claim to show the necessary leadership in the concerted effort of avoiding warming of 2°C in a diverse global context.

The outcome from the December 2012 climate negotiations in Doha has clarified the rules regarding surplus units for the Kyoto Protocol. We summarize these new rules and estimate the resulting effective emissions during the second commitment period using our unit trade model. Other options to deal with surplus emission allowances are employed as benchmarks to assess the Doha outcome. The effective emissions for developed countries as a group under the Doha outcome could be 10–11%below 1990 levels or 4–5%points below business-as-usual levels for the second commitment period if we assume that non-Kyoto Protocol countries domestically achieve their targets. However, if mechanisms exist where non-Kyoto Protocol countries can trade units, their emissions could increase and effective emis- sions for developed countries could be 7–8%below 1990 levels. In this low-ambition situation we find the main impact of theDoha surplus rules to be the introduction of the historical cap on emissions allowances. Without the effect of the cap, the Doha outcome allows the Parties to the second commitment period to emit at business- as-usual levels until 2020, while still leaving surplus units at the end of the second commitment period.

National action on climate change mitigation appears to be joining the international climate negotiations in the new and ever popular “climate shuffle” dance. It involves maximum effort and motion while staying in the same spot…or even, in some cases, going backwards. Recent emissions trends and estimates of the effects of those policies in place and proposed lead to a new estimate that warming is likely to approach 4°C by 2100, significantly above the warming that would result from full implementation of the pledges (3.3°C). The continuous global fossil-fuel intensive development of the past decade suggests that high warming levels of 4°C are more plausible than assuming full implementation of current pledges. Evidence is ever increasing that existing and planned policies are not sufficient for countries to meet these pledges. Emissions

Governments are still set to send global temperatures above 3°C by 2100, even though their agreed warming limit of 2°C is still technically possible, scientists said today. In this update we discuss the 2°C and 1.5°C limits, the future of the Kyoto Protocol and recent clarifications of Parties’ conditionality to move to their higher ambition pledges. In the second part we take a look at developments at the national level that are interesting for the international climate negotiations.

It is well known that the spacetime diagrams of some cellular automata have a self-similar fractal structure: for instance Wolfram’s rule 90 generates a Sierpinski triangle. Explaining the self-similarity of the spacetime diagrams of cellular automata is a well-explored topic, but virtually all of the results revolve around a special class of automata, whose typical features include irreversibility, an alphabet with a ring structure, a global evolution that is a ring homomorphism, and a property known as (weakly) p-Fermat. The class of automata that we study in this article has none of these properties. Their cell structure is weaker, as it does not come with a multiplication, and they are far from being p-Fermat, even weakly. However, they do produce self-similar spacetime diagrams, and we explain why and how.

older publications

It is well-known that the spacetime diagrams of some cellular automata have a fractal structure: for instance Pascal's triangle modulo 2 generates a Sierpinski triangle. Explaining the fractal structure of the spacetime diagrams of cellular automata is a much explored topic, but virtually all of the results revolve around a special class of automata, whose typical features include irreversibility, an alphabet with a ring structure, a global evolution that is a ring homomorphism, and a property known as (weakly) p-Fermat. The class of automata that we study in this article has none of these properties. Their cell structure is weaker, as it does not come with a multiplication, and they are far from being p-Fermat, even weakly. However, they do produce fractal spacetime diagrams, and we explain why and how.

Clifford quantum cellular automata (CQCAs) are a special kind of quantum cellular automata (QCAs) that incorporate Clifford group operations for the time evolution. Despite being classically simulable, they can be used as basic building blocks for universal quantum computation. This is due to the connection to translation-invariant stabilizer states and their entanglement properties. We will give a self-contained introduction to CQCAs and investigate the generation of entanglement under CQCA action. Furthermore, we will discuss finite configurations and applications of CQCAs.

We consider Clifford Quantum Cellular Automata (CQCAs) and their time evolution. CQCAs are an especially simple type of Quantum Cellular Automata, yet they show complex asymptotics and can even be a basic ingredient for universal quantum computation. In this work we study the time evolution of different classes of CQCAs. We distinguish between periodic CQCAs, fractal CQCAs and CQCAs with gliders. We then identify invariant states and study convergence properties of classes of states, like quasifree and stabilizer states. Finally we consider the generation of entanglement analytically and numerically for stabilizer and quasifree states.